Математика помогите!!!

A)
$y=-x^{2}+4x \ y=0 \ x=2 \\ -x^{2}+4x=0 \\ -x(x-4)=0 \\ x=0 \ x= 4 \\ S=\int \limits^0_2(-x^{2}+4x)dx = \mid^0_2(-\frac{x^{3}}{3}+2x^{2}) \\ -\frac{8}{3}+8=-\frac{16}{3}$

b)
$y=cosx \\ y=0 \ x=-\frac{\pi}{6} \ x=\frac{\pi}{6} \\ S=\int \limits^\frac{-\pi}{6}_\frac{\pi}{6}(cosx)dx \\ \mid^\frac{-\pi}{6}_\frac{\pi}{6}(-sinx)=\mid^\frac{5\pi}{6}_\frac{\pi}{6}-sinx \\ -\frac{1}{2}-\frac{1}{2}=-1$

v)
$y=x^{2} \ y=x+2 \\ x^{2}=x+2 \\ x^{2}-x-2=0 \\ x_{1}=2 \ x_{2}=-1 \\ S=\int\limits^2_1=\mid^1_2 \frac{x^{2}}{2}+2x=\frac{-3}{2}+6=-\frac{15}{2} \\ S=-3+\frac{15}{2}=\frac{9}{2}$